The present invention relates to black high temperature emissivity paint.
Black high temperature emissivity paints are used in the development, or operation, of gas turbine engines. Black high temperature emissivity paints are applied to components of gas turbine engines and the gas turbine engine is run at the gas turbine engines normal operating conditions. The component coated with the black high temperature emissivity paint is viewed by an optical pyrometer and the optical pyrometer is used to determine the temperature of the component. The pyrometer measures the energy radiated by the component. The temperature is determined because the emissivity of the black high temperature emissivity paint is known.
Existing black high temperature emissivity paint changes colour at temperatures of 900xc2x0 C. and greater and hence the emissivity of the black high temperature emissivity paint changes. Thus it may be necessary to recalibrate the pyrometer at different temperatures to take into account the change in colour, and emissivity, of the black high temperature emissivity paint at different temperatures.
There is a requirement for black high temperature emissivity paint whose colour remains unchanged at temperatures of 1100xc2x0 C. and greater.
Accordingly the present invention seeks to provide a novel black high temperature emissivity paint whose colour remains unchanged at temperatures of 1100xc2x0 C. and greater.
Accordingly the present invention provides a black high temperature emissivity paint comprising a black pigment, a binder and a solvent, the black pigment comprising (Co,Fe) (Fe,Cr)2 O4 and Ni.
Preferably the binder comprises acrylic resin and silicone resin.
Preferably the black high temperature emissivity paint comprises 25 wt % to 35 wt % black pigment, 40 wt % to 60 wt % acrylic resin and 20 wt % to 30 wt % silicone resin excluding solvent.
Preferably the black high temperature emissivity paint comprises 27.5 wt % black pigment, 50.5 wt % acrylic resin and 22 wt % silicone resin excluding solvent.
Preferably the solvent comprises a mixture of propylene glycol ethers.
Preferably the solvent comprises a mixture of 80% 1-methoxy-2-propanol and 20% dipropylene glycol monomethyl ether.